I need help with percentages can you please help im failing my math because of it

Asoccer ball manufacturer wants to estimate the mean circumference of soccer balls within 0.1 in

What is the factor form of x^2-9x+14

How many liters of peroxide should be added to 12 liters of an 8% peroxide solution so that the resulting solution contains 16% peroxide?   original added new amount of peroxide 0.96 liters x 0.96 + x amount of solution 12 liters x 12 + x 0.18 liter 1.14 liters 1.92 liters 2.10 liters